Evaluate the following expression when $y = 8$ and $x = 7$. $5$ $y$ $ + 8$ $x$ $ - 7$
Solution: Substitute $8$ for ${y}$ and $7$ for ${x}$ $ = 5{(8)} + 8{(7)} - 7 $ $ = 40 + 56 - 7 $ $ = 89$